8154387: Parallel unordered Stream.limit() tries to collect 128 elements even if limit is less

Reviewed-by: psandoz

src/share/classes/java/util/stream/StreamSpliterators.java

@@ -28,6 +28,7 @@ import java.util.Comparator;
 import java.util.Objects;
 import java.util.Spliterator;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.BooleanSupplier;
 import java.util.function.Consumer;
@@ -905,6 +906,7 @@ class StreamSpliterators {
         // The spliterator to slice
         protected final T_SPLITR s;
         protected final boolean unlimited;
+        protected final int chunkSize;
         private final long skipThreshold;
         private final AtomicLong permits;
 
@@ -912,6 +914,8 @@ class StreamSpliterators {
             this.s = s;
             this.unlimited = limit < 0;
             this.skipThreshold = limit >= 0 ? limit : 0;
+            this.chunkSize = limit >= 0 ? (int)Math.min(CHUNK_SIZE,
+                ((skip + limit) / AbstractTask.LEAF_TARGET) + 1) : CHUNK_SIZE;
             this.permits = new AtomicLong(limit >= 0 ? skip + limit : skip);
         }
 
@@ -921,6 +925,7 @@ class StreamSpliterators {
             this.unlimited = parent.unlimited;
             this.permits = parent.permits;
             this.skipThreshold = parent.skipThreshold;
+            this.chunkSize = parent.chunkSize;
         }
 
         /**
@@ -1029,13 +1034,13 @@ class StreamSpliterators {
                 PermitStatus permitStatus;
                 while ((permitStatus = permitStatus()) != PermitStatus.NO_MORE) {
                     if (permitStatus == PermitStatus.MAYBE_MORE) {
-                        // Optimistically traverse elements up to a threshold of CHUNK_SIZE
+                        // Optimistically traverse elements up to a threshold of chunkSize
                         if (sb == null)
-                            sb = new ArrayBuffer.OfRef<>(CHUNK_SIZE);
+                            sb = new ArrayBuffer.OfRef<>(chunkSize);
                         else
                             sb.reset();
                         long permitsRequested = 0;
-                        do { } while (s.tryAdvance(sb) && ++permitsRequested < CHUNK_SIZE);
+                        do { } while (s.tryAdvance(sb) && ++permitsRequested < chunkSize);
                         if (permitsRequested == 0)
                             return;
                         sb.forEach(action, acquirePermits(permitsRequested));
@@ -1102,15 +1107,15 @@ class StreamSpliterators {
                 PermitStatus permitStatus;
                 while ((permitStatus = permitStatus()) != PermitStatus.NO_MORE) {
                     if (permitStatus == PermitStatus.MAYBE_MORE) {
-                        // Optimistically traverse elements up to a threshold of CHUNK_SIZE
+                        // Optimistically traverse elements up to a threshold of chunkSize
                         if (sb == null)
-                            sb = bufferCreate(CHUNK_SIZE);
+                            sb = bufferCreate(chunkSize);
                         else
                             sb.reset();
                         @SuppressWarnings("unchecked")
                         T_CONS sbc = (T_CONS) sb;
                         long permitsRequested = 0;
-                        do { } while (s.tryAdvance(sbc) && ++permitsRequested < CHUNK_SIZE);
+                        do { } while (s.tryAdvance(sbc) && ++permitsRequested < chunkSize);
                         if (permitsRequested == 0)
                             return;
                         sb.forEach(action, acquirePermits(permitsRequested));